Dielectric heating of foamable compositions

An article produced by the process comprising:

• a. providing a first substrate;
• b. providing a second substrate;
• c. applying a composition in an uncoalesced state between the first substrate and the second substrate, wherein the composition comprises an (i) emulsion polymer having an initial water content of from about 35 wt % to 60 wt %, and (ii) and a plurality of expandable microspheres configured to expand at a temperature from an initial expansion temperature Texp of from about 80° C. to about 105° C. to a maximum expansion temperature of Tmax of from about 90° C. to about 140° C.;
• d. heating the composition for less than 1 minute using dielectric heating to expand the composition from a pre-expansion thickness to a post-expansion thickness that is from 77% to 81% greater than the pre-expansion thickness to form a foamed composition;
• and
• e. applying an adhesive between the first and the second substrate before, concurrently, or after the composition is applied between the first substrate and the second substrate;
• and
• wherein the foamed composition has from 0% to 15% of not expanded composition following the heating step,
• wherein the article has less than 10% wrinkles on a total surface area of the article, and
• wherein at least one of the first substrate or the second substrate is a fiberboard, a corrugated board, a solid bleached board, kraft paper, or coated paper.